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Trapped Radiation ENvironment model Development

TREND-1

The radiation environment models of the Earts have been reviewed and reevaluated. Several limitations of the earliers Erth's radiation models and of the way they have been used in the past for dose predictions along orbits of future spacecraft are identified and discussed in this report procuced by the TREND study team.

A new Solar Proton Events statistical model has been documented and implemented in the UNIRAD software used by ESA for expected dose calculations. Two sets of trapped electron flux measurements from LANL and IUE satellites have been analysed and compared to the existing NASA model predictions. These new data analysis confirm that the existing models predict in general too high radiation fluxes and therefore too high radiation doses. This leads aerospace engineers to build too thick and heavy shields to protect high sensitive electronic components or space habitacles for manned spaceflights. The TREND study has shown the urgent need for continued updating of space environment models. Recommendations and directions for future developments in modelling the radiation environment of the Earth have been given in the Final Report of TREND.

Radiation damage in outer space is one of the problems confronting any mission in orbit above the protective shield formed by the Earth's atmosphere.  The radiation environment above is quite complex, varying by orders of magnitudes both with altitude and time.  It effects sensitive microelectronics devices and the operation requirements for manned missions.

In this study it is proposed

  • to evaluate existing models of the Earth's radiation environment
  • to identify their limitations, and to outline requirements for future generation of environmental models
  • to identify the relevant particle measurements which are available to improve existing Earth's radiation environment models
  • to analyse some of these data and contribute a new step to longterm modelling efforts whiwh started at NSSDC/WDC-A-R&S in the 60's
  • to make recommendation for future flight measurements and monitoring of the Earth's radiation environment

Project made under ESA/Contract No. 9011/88/NL/ MAC